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OPERATIONAL AMPLIFIERS

OPERATIONAL AMPLIFIERS. Why do we study them at this point???. 1. OpAmps are very useful electronic components. 2. We have already the tools to analyze practical circuits using OpAmps. 3. The linear models for OpAmps include dependent sources. TYPICAL DEVICE USING OP-AMPS . LM324 DIP.

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OPERATIONAL AMPLIFIERS

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  1. OPERATIONAL AMPLIFIERS Why do we study them at this point??? 1. OpAmps are very useful electronic components 2. We have already the tools to analyze practical circuits using OpAmps 3. The linear models for OpAmps include dependent sources TYPICAL DEVICE USING OP-AMPS

  2. LM324 DIP LMC6294 MAX4240 OP-AMP ASSEMBLED ON PRINTED CIRCUIT BOARD APEX PA03 DIMENSIONAL DIAGRAM LM 324 PIN OUT FOR LM324

  3. OUTPUT RESISTANCE INPUT RESISTANCE TYPICAL VALUES GAIN CIRCUIT SYMBOL FOR AN OP-AMP SHOWING POWER SUPPLIES LINEAR MODEL

  4. LOAD OP-AMP DRIVING CIRCUIT CIRCUIT WITH OPERATIONAL AMPLIFIER

  5. TRANSFER PLOTS FOR SOME COMERCIAL OP-AMPS SATURATION REGION LINEAR REGION OP-AMP IN SATURATION IDENTIFY SATURATION REGIONS

  6. PERFORMANCE OF REAL OP-AMPS CIRCUIT AND MODEL FOR UNITY GAIN BUFFER WHY UNIT GAIN BUFFER? BUFFER GAIN

  7. THE IDEAL OP-AMP

  8. USING LINEAR (NON-IDEAL) OP-AMP MODEL WE OBTAINED PERFORMANCE OF REAL OP-AMPS THE UNITY GAIN BUFFER – IDEAL OP-AMP ASSUMPTION IDEAL OP-AMP ASSUMPTION YIELDS EXCELLENT APPROXIMATION!

  9. CONNECTION WITHOUT BUFFER CONNECTION WITH BUFFER WHY USE THE VOLTAGE FOLLOWER OR UNITY GAIN BUFFER? THE VOLTAGE FOLLOWER ACTS AS BUFFER AMPLIFIER THE VOLTAGE FOLLOWER ISOLATES ONE CIRCUIT FROM ANOTHER ESPECIALLY USEFUL IF THE SOURCE HAS VERY LITTLE POWER THE SOURCE SUPPLIES NO POWER THE SOURCE SUPPLIES POWER

  10. LEARNING EXAMPLE

  11. OUTPUT CURRENT IS NOT KNOWN THE OP-AMP IS DEFINED BY ITS 3 NODES. HENCE IT NEEDS 3 EQUATIONS KCL AT V_ AND V+ YIELD TWO EQUATIONS (INFINITE INPUT RESISTANCE IMPLIES THAT i-, i+ ARE KNOWN) DON’T USE KCL AT OUTPUT NODE. GET THIRD EQUATION FROM INFINITE GAIN ASSUMPTION (v+ = v-) LEARNING EXAMPLE: DIFFERENTIAL AMPLIFIER THINK NODES!

  12. IDEAL OP-AMP CONDITIONS LEARNING EXAMPLE: DIFFERENTIAL AMPLIFIER NODES @ INVERTING TERMINAL NODES @ NON INVERTING TERMINAL

  13. LEARNING EXAMPLE: USE IDEAL OP-AMP USE REMAINING NODE EQUATIONS ONLY UNKWONS ARE OUTPUT NODE VOLTAGES FINISH WITH INPUT NODE EQUATIONS… USE INFINTE GAIN ASSUMPTION 6 NODE EQUATIONS + 2 IDEAL OP-AMP

  14. LEARNING EXTENSION

  15. SET VOLTAGE “inverse voltage divider” INFINITE GAIN ASSUMPTION INFINITE INPUT RESISTANCE LEARNING EXTENSION NONINVERTING AMPLIFIER - IDEAL OP-AMP

  16. UNDER IDEAL CONDITIONS BOTH CIRCUITS SATISFY LEARNING EXAMPLE DETERMINE IF BOTH IMPLEMENTATIONS PRODUCE THE FULL RANGE FOR THE OUTPUT EXCEEDS SUPPLY VALUE. THIS OP-AMP SATURATES! POOR IMPLEMENTATION

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